Surface Properties Of Materials Research Articles

TEM and X-ray diffraction studies of structure of TiNi SMA treated by low-energy high-current electron beam

Advanced scientific and technological achievements in the surface engineering of TiNi shape memory alloys are closely related with their mechanical performance. Electron-beam treatments could be applied in order to modify surface properties of smart materials and promote stress-induced martensitic transformations. The fundamental issue of electron-beam processing is residual elastic stresses arising from the ultrafast quenching (∼108 K/s) of thin (∼2–4 μm) surface layers. We report the experimental results on phase composition, structure and residual elastic stresses formed in the binary TiNi SMA irradiated by a low-energy (< 25 keV) high-current (∼ 25 kA) electron beam. Microstructure, fracture mechanisms and phase analysis of the as-cast and deformed tensile specimens have been studied by X-ray diffraction and electron microscopy. After electron-beam treatment, both martensitic B19′ and R phases are found in the near surface layer. The X-ray diffraction studies indicate that compressive stresses in the B2 phase of the irradiated TiNi alloy reach –460 MPa. In the fractured specimen (after tensile test) the residual stresses decrease to –160 MPa and release through the B2→B19′→B2 martensitic transformation. In-depth gradient distribution of the defect substructures responsible for the mechanical behavior of TiNi alloys was revealed.

Tailless Information-Energy Metasurface.

Programmable metasurface technology can achieve flexible manipulations of electromagnetic waves in real time by adjusting the surface structure and material properties and has shown extraordinary potential in many fields such as wireless communications and the Internet of Things. However, most of the programmable metasurfaces have a common feature: a tail (electrical wires and DC powers), which is difficult to supply in some particular application scenarios such as canyons and mountains. To eliminate the limitation of DC power supply, the programmable metasurface and wireless power transfer technology are combined to propose a tailless information-energy metasurface (IEMS). The tailless IEMS platform can dynamically control electromagnetic waves without relying on an external DC power supply; instead, the required DC power is provided internally by the IEMS platform itself. In the tailless IEMS experiments, the concept is demonstrated through the dynamic regulation of wireless channels and the wireless transmission of DC power. This work provides a self-powered method for programmable metasurfaces, expands the application scenarios, facilitates the miniaturization of systems, and makes it easy to integrate with other systems.

Optical and microstructural properties of electrodeposited cuprous oxide

The production of hydrogen fuel using photoelectrochemical water splitting method requires semiconductor materials with suitable energy gap, electrical and optical properties. Cuprous oxide is feasible candidate fulfilling many of these requirements to be the photocathode of such devices. In this study, we investigated optical and microstructural properties of cuprous oxide prepared under different temperatures. Microstructure properties were evaluated by statistical, fractal and Fourier methods. Roughness characteristics, Fourier transforms and multifractal characteristics provide consistent information connected with the distribution of surface objects created during sample fabrication. Our methodology is feasible to provide practical insights for the fabrication and monitoring of surface and optical properties of Cu2O and other semiconductor materials.

Remotely Controlled Electrochemical Degradation of Metallic Implants.

Biodegradable medical implants promise to benefit patients by eliminating risks and discomfort associated with permanent implantation or surgical removal. The time until full resorption is largely determined by the implant's material composition, geometric design, and surface properties. Implants with a fixed residence time, however, cannot account for the needs of individual patients, thereby imposing limits on personalization. Here, an active Fe-based implant system is reported whose biodegradation is controlled remotely and in situ. This is achieved by incorporating a galvanic cell within the implant. An external and wireless signal is used to activate the on-board electronic circuit that controls the corrosion current between the implant body and an integrated counter electrode. This configuration leads to the accelerated degradation of the implant and allows to harvest electrochemical energy that is naturally released by corrosion. In this study, the electrochemical properties of the Fe-30Mn-1C/Pt galvanic cell model system is first investigated and high-resolution X-ray microcomputed tomography is used to evaluate the galvanic degradation of stent structures. Subsequently, a centimeter-sized active implant prototype is assembled with conventional electronic components and the remotely controlled corrosion is tested in vitro. Furthermore, strategies toward the miniaturization and full biodegradability of this system are presented.

Flexible Pressure Sensor Based on Carbon Black/PVDF Nanocomposite

A piezoresistive flexible pressure sensor was fabricated using carbon black and Poly (vinylidene fluoride) (CB/PVDF) composite. The conductive CB/PVDF composite was prepared by a wet-cast method and deposited onto a flexible polyethylene (PE) substrate. The surface morphology, crystal structure, and material properties were studied using SEM and X-ray diffraction methods. This flexible pressure sensor was tested in a wide pressure range of about 0 - 76 kPa, and its response time was less than 0.43 s. The sensitivity, response time, and recovery time were studied for different pressures and vibration modes. The repeatability and reproducibility characteristics of the sensors were studied, and it was found that the sensors exhibited excellent characteristics. The sensor was subjected to different loading and unloading pressures, and the resistance of the sensor remained stable, indicating that the sensor had a high degree of reproducibility. Owing to its flexible properties and the materials used, the proposed device can be applied in the next generation of smart sensors for biomedical, robotic, and automotive sensing applications.

Geometric attenuation function analysis based on V-grooved surfaces.

In this study, we present a simulation addressing the phenomena of shadowing and masking in TE and TM polarized incident plane waves interacting with V-grooved rough surfaces. Blinn's theory on light attenuation posits that such a rough surface is represented by a symmetric, elongated V-shaped groove cavity, considering only the tilt angles of the slopes. Our numerical analysis considers variables such as polarization (TE or TM), wavelength, tilt, and slant of the incident or viewing direction, as well as the material properties of the rough surfaces, to accurately calculate light attenuation on V-grooved rough surfaces. The findings indicate enhanced precision in the measurement of light attenuation on these complex geometries.

Preparation and Properties of Novel Antimicrobial Polyurethane Materials

Using the pre-polymer method, we created new materials called antimicrobial polyurethane (PU). To analyze the chemical structures of the PU materials, we used various techniques, including Fourier transform infrared (FTIR), 1H-NMR, gel permeation chromatography (GPC), and Differential Scanning Calorimetry (DSC). In addition, we investigated the surface properties of the PU material by scanning electron microscopy (SEM). According to the mechanical assessment, the antimicrobial polyurethane films display good mechanical qualities. We have also tested the barrier and antimicrobial properties of the films, and the results show that these films have good barrier properties and that the antimicrobial polyurethane films have better antimicrobial properties compared to pure polyurethane films. These properties are enhanced as the antimicrobial agent content in the antimicrobial polyurethane films increases.

Structural, optical and magnetic properties of Fe, Co and Co[sbnd]Fe doped SnO2 thin films deposited by a thermionic vacuum arc deposition system

Fe, Co and CoFe doped SnO2 thin films were deposited onto glass, indium tin oxide-coated glass, and Si substrates to investigate the influence of substrate material on the surface and magnetic properties. The motivation of this study is to investigate the magnetic, surface, and optical properties of doped SnO2 semiconductor materials as they vary with different substrate materials. The film surfaces are smooth and compact. Additionally, nano particles were observed. Thin films of SnO2 doped with Fe, Co and CoFe doped SnO2 have a Curie temperature. Magnetization–temperature and magnetization–temperature graphs have shown the predicted magnetic properties. These films have giant magnetization and soft magnetic properties. In separately doped Fe and Co – SnO2 thin films, the M (emu) values are nearly the same. In Co and Fe-doped SnO2 thin films, the M (emu) values for the film deposited onto ITO-coated glass and uncoated glass are nearly the same.

Effect of the Addition of Naringenin Derived from Citrus on the Properties of Epoxy Resin Compositions.

This research concerns the modification of commercially available epoxy resin with flame retardants in order to obtain aging-resistant and antimicrobial polymeric materials with a plant stabilizer dedicated to use in rail transport. Polymer compositions based on epoxy resin, fiberglass fabric, and naringenin were prepared. Naringenin was added as a natural stabilizer at 2, 4, and 8 phr. The materials were subjected to solar aging lasting 800 h. The hardness of the samples, surface energy, and carbonyl indexes were determined, and the color change in the composition after aging was analyzed. In addition, microscopic observations, analyses of mechanical properties, and microbiological tests were performed. The hardness determination showed that the samples retained their functional properties after solar aging. The increase in the polar component of the surface energy of all materials indicated the beginning of the degradation process of the composites. The tensile one-directional tests were carried out for plane samples taken in three directions (0, 90, and 45 degrees referred to a plate edge) before and after the aging process. The addition of naringenin did not affect the functional and surface properties of the epoxy resin-based materials. Polyphenol stabilized polymer composites, as evidenced by the results of carbonyl indexes. Moreover, the obtained samples showed good antimicrobial properties for E. coli and C. albicans in the field of testing the viability of microbial cells in contact with the tested surfaces.

A review on the environment friendly electroplating of Cr (III) &amp; Cr (VI)

Chromium plating process is the most effective way of protecting the base material against hostile environment or improving surface properties of base material. There are several problems with traditional chrome plating. Traditional process uses toxic acid baths and may cause various health conditions. The baths employed contain chromic acid in which the chromium is in the hexavalent state. Hexavalent chromium has been proved to have toxic, mutagenic and cancerogenic effects for human health. As a result, In Europe, the implementation of the reach initiative will increase fees on companies still using Cr (VI) in 2017 and will require action plans to phase out Cr (VI) in the future. This has left the plating industry in a very delicate position with dark future prospects unless new solutions that are both effective and environmentally friendly are discovered. Superchrome Physical Vapor Deposition coating ahead of looming industry regulatory actions that will drive towards the removal of hazardous hexavalent chromium compounds. These new sputtered chromium coatings do not require a protective paint top coat to pass exterior automotive trim specifications. Visually the chromium coatings match those of electroplated decorative chromium in color and appearance.

Thermal analysis for laminated plates with arbitrary supports under non-uniform temperature boundary conditions

This paper aims to investigate thermal behaviors of composite laminated plates with different supports under non-uniform temperature boundary conditions. The thermo-elastic solutions of temperature, displacements, and stresses for the laminated plate with arbitrary layer numbers and thickness are obtained based on the three-dimensional theory of thermoelasticity. By applying the Fourier law of heat conduction and the thermoelastic equations, the state-space equations are established by employing the temperature, heat flux, displacements, and stresses as state variables without the hypothesis of displacement form. The differential quadrature method is introduced to discretize the in-plane state variables. On the basis of the continuities of state variables at the interfaces in the laminated plate, the relationships of temperature, heat flux, displacements, and stresses between the top and bottom surfaces can be derived. By simultaneously considering temperature and mechanical boundary conditions applied to the surfaces of the laminated plate, the initial state variables for temperature, displacements, and stresses can be determined uniquely. The errors in the temperature, displacements and stresses resulting from the differential quadrature method can be eliminated by incrementally augmenting the number of sampling points in the convergence study. The accuracy of the present method is thoroughly verified by comparing the current results with both the finite element solutions and the findings reported in previous literature. Finally, the influences of surface temperature, length-to-thickness ratios, material properties, layer numbers, and support types for the distributions of the temperature field, displacements, and stresses in the laminated plate are discussed in detail.

Evaluating the biocompatibility of ceramic materials for constructing artificial reefs

IntroductionCoastal ecosystems, including reefs, are becoming increasingly threatened as anthropogenic development continues to encroach on intertidal habitats with little initiative to establish ecologically considerate infrastructure. Submerging human-made, shelter-providing structures known as artificial reefs (AR) can contribute to the preservation of these ecosystems. ARs are historically used for promoting the abundance and biodiversity of marine species for aquaculture, conservation, and ecotourism; and are typically made of concretes or metal structures. An AR’s success correlates to its ability to establish a surface layer of microorganisms, such as microalgae and bacteria, known as a biofilm. The productivity of the biofilm can be influenced by material surface properties. It is hypothesized that material pH and porosity affect the rate of biofilm formation.MethodsHere - a range of concrete mixtures were cast and submerged in circulating seawater and mass per surface area of biofilm accumulation was measured to evaluate this theory. These mixtures included standard Portland Cement (PC), PC with admixtures of diatomaceous earth (PDC) and limestone (PLC), fine-aggregate high-performance concrete (DUC), and terra cotta (TER). ARs were manufactured as 38mm tall cylinders, 76mm in diameter, and submerged in circulating seawater to evaluate mass per surface area of biofilm accumulation.ResultsOur results indicate that biofilm formation is directly affected by surface porosity and less-so by pH, as determined by measuring material properties after submersion. We found that the PDC samples were most successful in forming a biofilm despite being more fragile than other concrete samples.DiscussionThis preliminary study provides insight into how different material properties influence the accumulation of biofilm as a starting point for designing ARs. Future work will investigate the long-term performance of such samples in relevant conditions.

Construction of dual receptors imprinted polymers by precise control of sequential assembly efficiency in confined sites to enhance specific separation of adenosine 5′-monophosphate

Sequential assembly strategies are employed to incorporate various monomers, thereby enhancing the specific binding capability of imprinting sites towards the target molecule and ultimately improving the selectivity of molecular imprinted polymers (MIPs). However, the effectiveness of sequential assembly in improving discriminative separation requires further investigation. For the specific functional groups present in AMP molecules, the utilization of confining metal ion sites guided by metal–organic frameworks (MOFs) material can effectively mitigate disordered competition, enhance the efficiency of imprinted assembly, and facilitate the controlled growth of imprinted sites. In this study, we have successfully achieved precise control over the efficiency of sequential assembly in hydrophilic Zr-MOFs nanosheets in order to fabricate dual receptor surface molecularly imprinted sorbents (D-MIPs) for selectively separating AMP. The hydrophilic Zr-MOFs nanosheets (D-PABA) possess a significantly high surface area of approximately 282.52 m2 g−1. The water contact angle of Zr-BTB-FA nanosheets was measured to be 32°, while that of D-MIPs was 25°. The hydrophilic surface properties of materials promote the dispersion of the adsorbent in aqueous solutions and enhance the rapid mass transfer of water-soluble target molecules. Additionally, the half-equilibrium time (t1/2) was found to be 0.578 h. The D-MIPs demonstrate a significant adsorption capacity (286.7 μmol g−1 at 298 K) for AMP compared to other nucleoside analogues, such as dC, dG, dA, ADP and ATP. Additionally, an imprinting factor (IF) of 2.764 was observed for D-MIPs compared to their non-imprinted counterpart. In addition, the selective extraction of 97 % AMP from the spiked diluted biofermentation broth sample can be achieved using D-MIPs. This finding highlights the potential of D-MIPs as an efficient solution for the selective capture of AMP from biological samples.

Effect of Laser Surface Modification on Texture, Roughness, Wettability and Surface Energy of Hastelloy C22, C276 &amp;amp; X

Hastelloy is a nickel-chromium-molybdenum-iron-based alloy and a member of the ‘superalloy’ family. Hastelloy has exceptional properties like high strength, wear resistance and high-temperature stress-corrosion resistance. Therefore, Hastelloy is used in gas turbines, power plants, metal injection molding, etc. Many industrial applications are related to the properties of the surface. Wettability is a key surface property that affects applications like lubrication, adhesion, coating, heat conduction, etc. Laser Texturing is an excellent method to modify the surface properties of materials like metal, polymers and ceramic. In the present study, a carbon dioxide laser created unidirectional textures on Hastelloy (C22, C276, X). Different sets of unidirectional textures were formed by changing the laser power and frequency. Various roughness parameters were compared for every laser parameter. In this paper, the effective change in wettability properties of Hastelloy (C22, C276, X) after the Laser texturing process for a range of power and frequency were studied under DI water and glycerol as test fluids. Results show that the contact angle of the test fluid increases as the laser power increases, and the contact angle decreases as the laser frequency increases for all three superalloys. The surface energy of a given set of samples was also measured using the recorded contact angle of DI water and Glycerol by the OWRK equation. Similar trends were found in surface energy for all three Hastelloy.

Polyacrylonitrile-sodium lignosulfonate -derived nitrogen-doped three-dimensional hierarchical porous carbon for supercapacitors

Modulation of pore structure and heteroatom doping are very important strategies to improve the electrochemical properties of carbon electrode materials. This report investigates the use of biomass-derived nitrogen-doped porous carbon materials to address the challenge of the specific capacitance and energy density in supercapacitors. Nitrogen-doped three-dimensional hierarchical porous carbon materials were prepared using a polyacrylonitrile/sodium lignosulfonate composite monolith as a precursor by thermally induced phase separation and subsequent carbonization/activation. This method precisely controls the structure and surface properties of porous carbon materials by regulating the structure of the precursor and situ doping of nitrogen, which is a valuable strategy for the controllable regulation of the pore structure for nitrogen-doped porous carbon materials. The resulting carbon material displayed excellent capacitance performance, exhibiting a high specific capacitance of 325.7F g -1 at a current density of 0.5 A/g, maintaining initial capacitance retention of 90.1 % at a current density of 5 A/g after 10,000 cycles. When investigated for practical applications, the assembled supercapacitor device had a higher energy density (9.88 W h kg- 1), which is higher than commercial carbon-based supercapacitors.

Potential application of carboxymethyl cellulose/sodium alginate aerogels loaded with algal biomass for disinfection of contaminated water

Many developing countries still lack enough credentials for a healthy and safe water supply. To control the circulation of waterborne diseases and ensure consumer safety, a significant problem is eliminating dangerous microbes from water systems using efficacious water disinfection technology. This current research work's objective was to encapsulate the algal biomass inside the porous structures of these sponge materials. Freeze drying technique was used to prepare these sponge materials using carboxymethyl cellulose (CMC) and sodium alginate (SA). The aerogel solution was loaded with different concentrations of algal biomass. The algal biomass was encapsulated owing to the presence of many interstitial pores with these spongy materials. The obtained data depicted that aerogels exhibited lamellar layers with immense porous structures. The mechanical properties of aerogels were enhanced with the addition of algal biomass. Inactivating 100% of both Gram-negative and Gram-positive bacteria, including Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Enterococcus faecalis were achieved within 120 min after treatment by Sp.m-3 @CM-SA aerogel. The biocidal effect of the Sp.m-3 @CM-SA aerogel is thought to be controlled primarily by surface-controlled processes that rely on direct contact between the bacterial cells and the interface of the aerogel. This suggests that the antimicrobial activity of the aerogel is related to the material's surface properties, which may facilitate the release of antimicrobial compounds from the algal biomass loaded in the aerogel.

Analysis of microstructure, surface morphology, and scratch resistance of high velocity oxy-fuel coated nickel based hybrid nano-composites

In recent years, high velocity oxygen fuel (HVOF) coating technology has gained significant interest in the field of surface engineering. In this study, we have investigated the microstructure, surface morphology, and scratch resistance of HVOF coated Nickel based novel hybrid nano-composites. The coatings were prepared using a high-velocity oxy-fuel (HVOF). HVOF coatings have the ability to enhance the surface properties of various materials, making them more resistant to wear, corrosion, and erosion. Thermal spraying technique, and the microstructure and surface morphology of the coatings were analyzed using scanning electron microscopy (SEM). The scratch test was performed using a TR-101, DUCOM made Scratch tester to evaluate the scratch resistance of the coatings. The results of the study revealed that the HVOF coated novel hybrid nano-composites exhibited a fine-grained microstructure with a dense and homogeneous surface morphology. The scratch resistance of the coatings was significantly improved due to the addition of nano composites. The load required to cause the first visible scratch on the coated surface was found to be significantly higher than that of the uncoated substrate. The scratch morphology of the coatings was also studied, which revealed that the scratch-induced damage was mainly due to the plastic deformation of the coating material. The results suggest that the HVOF coated novel hybrid nano composites have great potential in improving the surface properties of various engineering materials and can be used in applications where high wear resistance is required. Overall, the study demonstrates that the combination of HVOF coating technology and hybrid nano-composites can result in coatings with improved microstructure, surface morphology, and scratch resistance, which makes them ideal for use in applications wherever wear resistance is critical.

Unravelling the role of pore structure of biomass-derived porous carbon in charge storage mechanisms for supercapacitors.

This study presents findings on the production and analysis of activated carbon (AC), which exhibits a significantly expansive surface area derived from readily available and inexpensive agroforestry waste, specifically coconut shells. The carbon materials displayed encouraging features for electrochemical energy storage applications with a high specific surface area (2920 m2 g-1), an ordered mesoporous structure (∼2.5 nm), and substantial electronic conductivity. By altering the surface properties of AC materials, they exhibited different energy storage responses while using an ionic liquid as an electrolyte. Electrodes composed of AC sourced from coconut shells demonstrated notably high specific capacitance (78 F g-1) and retained capacitance when assessed within symmetric electrical double-layer capacitors (EDLCs) employing organic electrolytes. Interestingly, the AC cell in an organic electrolyte delivered a specific energy (Es) of 67 W h kg-1 at a specific power (Ps) of 1237 W kg-1 at the current density of 1 A g-1 and still provided Es of 64, 60, 58, 57, and 52 W h kg-1 at Ps of 2477, 3724, 4971, 6218 and 12 480 W kg-1 at the current density of 2, 3, 4, 5 and 10 A g-1. This work demonstrates the effect of different pore volumes on the electrocatalytic activity of AC derived from natural product waste. Our results indicate the feasibility of employing these electrodes for lab-scale applications. Thus, the AC material emerges as a highly promising substance, poised to advance the creation of cost-efficient, environmentally sustainable, high-performance, high-power devices.

The osteoconductive properties of graphene-based material surfaces are finely tuned by the conditioning layer and surface chemistry

The molecular layer that adsorbs on the biomaterial surface upon contacting body tissues and fluids, termed the conditioning layer (CL), influences cell behavior regulating scaffold integration and resilience in a patient-specific fashion.

Accelerating the prediction of inorganic surfaces with machine learning interatomic potentials.

The surface properties of solid-state materials often dictate their functionality, especially for applications where nanoscale effects become important. The relevant surface(s) and their properties are determined, in large part, by the material's synthesis or operating conditions. These conditions dictate thermodynamic driving forces and kinetic rates responsible for yielding the observed surface structure and morphology. Computational surface science methods have long been applied to connect thermochemical conditions to surface phase stability, particularly in the heterogeneous catalysis and thin film growth communities. This review provides a brief introduction to first-principles approaches to compute surface phase diagrams before introducing emerging data-driven approaches. The remainder of the review focuses on the application of machine learning, predominantly in the form of learned interatomic potentials, to study complex surfaces. As machine learning algorithms and large datasets on which to train them become more commonplace in materials science, computational methods are poised to become even more predictive and powerful for modeling the complexities of inorganic surfaces at the nanoscale.